1. Field of the Invention
The present invention relates to a welding method and apparatus, and particularly to an electric welding method and apparatus using electrodes to weld a work which is sandwiched therebetween.
2. Description of the Prior Art
In welding a work it is moved left to right or vice versa along the X-axis, back and forth or vice versa along the Y-axis and up and down and vice versa, along the Z-axis until it has been put in the right position with respect to the electrodes. For the purpose of putting the work in a desired position at which required welding is effected, a servo motor or hydraulic motor is used. Usually a servo motor is used because it can put a workpiece exactly in a desired position with accuracy. A servo control for positioning a work with respect to the electrodes of a welding apparatus, permits quick and easy positioning of the work, accordingly improving the efficiency with which required welding is effected. However, it has the following disadvantages and demerits: (1) a servo motor is relatively expensive; (2) uses a high-level technical art, and accordingly its maintenance requires expert knowledge and skillfulness; and (3) nearmiss is often caused: a work is put in a desired position, and then the electrodes are moved to reach the work, and therefore sometimes the electrodes push and put the work away from the desired position. If the work is not firm or still enough to resist the push of the electrodes against the work, it may be bent or deformed. Then, the electrodes cannot fully contact the work, and poor welding will result.